AWS bill line item
USE1-Claude4.6Sonnet-cache-read-input-token-count
Tokens served from Bedrock's prompt cache (instead of being reprocessed as full input) appear as their own usage type, billed at a steep discount versus a normal input token.
Bedrock prompt-cache read tokens
Verified against official AWS documentation last checked
Why it shows up
This line item appears as soon as an application uses prompt caching on a supported model; teams who didn't know caching was enabled are often confused to see a brand-new, unfamiliar usage type appear on the bill even though it represents savings, not new spend.
The savings only materialize if the cache is being hit: for a bursty, low-repeat workload where cache-write volume dominates over cache-read, the cache overhead can cost more than it saves.
How to cut it
- Check the cache read-to-write ratio before assuming caching is saving money.
- Put static, reusable content (system prompt, shared context) first in the prompt so the cache prefix matches across calls.
- Only enable caching for workloads with repeated prompt prefixes, not one-off requests.
How to read this code
USE1 / USE2us-east-1 (N. Virginia) / us-east-2 (Ohio)
Source
Source: AWS docs →Found USE1-Claude4.6Sonnet-cache-read-input-token-count on your own bill?
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